Re: Speed of glCopyTexSubImage2D and back bandwidth

Where did you get the impression that the software renderer is not a
priority Jeff ?

On Oct 25, 2004, at 10:59 AM, Jeff Ray wrote:

I just wanted to confirm my understanding of glCopyTexSubImage2D:

If I have a texture format match (e.g. RGBA framebuffer and RGBA
texture) do I get an on-card copy? Is this on-card copy fast with
reasonably modern HW?

Yes, this should be a fast VRAM to VRAM copy. If it's not it's a bug
that should be filed with Apple.

What about the software-only case? Is there a similar optimization
for that? If not, is it worth it writing a feature request? (I
realize the software renderer isn't a big priority, and I appreciated
Apple keeping it around.)

I ask because I have a number of users who can only use the software
GL renderer, and had to revert to a Quickdraw-based renderer when I
added a feature that requires a single glCopyTexSubImage2D each frame.
If there were some way to speed this one call up, I could reclaim a
fair number of users.

I know p-buffers is a better solution, but I'm not quite ready to
refactor the code and rule out 10.2...

Using glCopyTexSubImage2D is a fine solution for most cases.

It would be nice if there were a concise "do this, don't do that"
available so I could know I'm doing everything I can to get best speed
from it.
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